Chemometric analysis and chemical characterization for the botanical identification of Glycyrrhiza species (G. glabra, G. uralensis, G. inflata, G. echinata and G. lepidota) using liquid chromatography-quadrupole time of flight mass spectrometry (LC-QToF)

Abstract

Licorice is obtained from the roots of several species of Glycyrrhiza (Fabaceae), a genus containing about 20 species. The Chinese Pharmacopeia specifies three Glycyrrhiza species (G. glabra, G. uralensis, G. inflata). In an effort to unambiguously differentiate roots of five Glycyrrhiza species (G. glabra, G. uralensis, G. inflata, G. echinata, and G. lepidota), a LC-QToF method integrated with chemometric tools has been applied, based on chemical profiling of two major classes of saponins and phenolics. Multivariate statistical analysis, together with mass fragmentation of protonated/deprotonated molecular species, resulted in diagnostic fragment ions which were helpful in identification of core structural skeletons as well as functional groups appended to core structures. Roots named in the Chinese Pharmacopeia showed higher content of the triterpene saponinglycyrrhizinalong with phenolics including species-specific components. Most species-specific components were confirmed by comparison with reference standards and were utilized in statistical models to differentiate aerial from root parts. This study investigated 105 licorice samples and 11 licorice dietary supplements using LC-QToF data combined with PCA and PLS-DA models. Species-specific markers including glabridin, glycybridins, hispaglabridins, glabrol from G. glabra, glycycoumarin, licoflavonol, licoisoflavone A/B from G. uralensis, and licochalcones A-E from G. inflata were identified. Additionally, macedonosides and yunganosides were identified from G. lepidota and G. echinata. The investigated licorice dietary supplements were found to contain G. glabra. Furthermore, this study demonstrated the usefulness of these tools for quality assessment of licorice products